Metals and Non-metals: 10th Science

Question: Give composition of the alloy – ‘brass’ and ‘bronze’.

Answer: Brass – Cu and Zn
Bronze – Cu and Tin

Question: What is the formula of rust?

Answer: Fe₂O₃.xH₂O.

Question: An alloy has low melting point and is, therefore, used for electrical fuse. Name they alloy and write its constituents.

Answer: Solder, Pb and Sn.

Question: Name one metal and a non-metal found in liquid state at room temperature.

Answer: Metal – mercury.
Non-metal – bromine.

Question: Name two metals which react with dilute HNO₃ to evolve H₂ gas.

Answer: Magnesium (Mg) and manganese (Mn).

Question: Why oxides of high reactive metals cannot be reduced by carbon?

Answer: This is because these metals have more affinity for oxygen than carbon.

Question: What is formed when sodium absorbs moisture from air? Give equation also.

Answer: It forms sodium hydroxide.
2Na + H₂O → 2NaOH + H₂

Question: Why the sulphide and carbonate ores are converted into oxides?

Answer: It is because it is easier to obtain a metal from its oxide, as compared to its sulphide and carbonates.

Question: From amongst the metals sodium, calcium, aluminium, copper and magnesium, name the metal:
(i) which reacts with water only on boiling, and
(ii) another which does not react even with steam.

Answer: (i) Magnesium    (ii) Copper.

Question: Name any one metal which reacts neither with cold water nor with hot water but heated steam to produce hydrogen gas.

Answer: Iron (Fe), aluminium (Al) and zinc (Zn) do not react either with cold or hot water. They react with steam to from metal oxide and hydrogen, e.g.,
3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)

Question: Name two metals which have very low melting point.

Answer: (i) Caesium    (ii) Gallium.

Question: Name is a non-metal which is lustrous and a metal which is non-lustrous.

Answer: Iodine is a non-metal which is lustrous. Iron is a metal which is non-lustrous.

Question: Write balanced chemical equation for the reaction: Aluminium when heated in air. Write the name of the product.

Answer:
4Al + 3O₂ →  2Al₂O₃ (Aluminium oxide)

Question: Why do ionic compounds electricity in the solid state.

Answer: Movement of ions in the solid state is not possible due to their rigid structure.